It is well known that a large amount of unreacted monomer may be lost during the process of Polymerization. The portion of this loss which is due to entrapped monomer represents an environmental hazard which augments the hazards posed to manufacturing workers. This is true not only for vinyl chloride monomer in polyvinyl chloride, but also other monomers entrapped in the corresponding polymer products such as polyacrylamide. This research project is designed to correlate the methods and conditions of polymerization with the entrapment of unreacted monomer and of low molecular weight compounds (dimer, trimer, etc.). The polymers proposed to be investigated are industrially significant materials such as polyacrylonitrile, polystyrene and polyvinyl chloride. Experimenal approaches will also include determinations of whether monomers, once they are entrapped in the polymer products can diffuse out of the polymers at a rate sufficient to lead to a significant concentration of monomers, e.g., under storage conditions or conditions of use in formulating and/or in heat-sealing applications. The primary purpose of the research will be to find methods whereby monomer entrapment may be minimized, and therefore any industrial or environmental hazards may be reduced.